Leucodonis distinguished from the other genera
of its family by its ecostate leaves and smooth calyptra. Forsstroemiais
similar but its plants are more glossy and the
leaves are variably costate. Also, according to L.
R. Stark (1985) paraphyses are present in the perichaetia of Forsstroemiabut
lacking in the perichaetia of Leucodon.

Leucodonjulaceus is very common and widespread in much
of the eastern portion of the flora area.The usually short, curved, julaceus
branches, smooth (nonplicate) leaves, and somewhat
glossy aspect are characteristic.Growth forms with slender elongate rhizome-like primary stems bearing
widely-spaced short, uncinate branches are very
different in appearance from more robust forms with inconspicuous primary
stems bearing straight elongate crowded branches.The forms with elongate slender primary sems sometimes form extensive soft tangled mats and then
may be mistaken for mosses of other families.In L. andrewsianus
and L. brachypus
the leaves are longer and more or less plicate; L. julaceus lacks the clustered fragile
branchlets of L.
andrewsianus.Its capsules are almost always well exserted beyond the perichaetial leaves, while the capsules of L. brachypus are partially
immersed.The calyptra
of L. julaceus
splits along one side and may for a time remain clasping the seta below the
capsule.It sometimes grips the tip of
the operculum, and when dry lifts the operculum to open the capsule, as in Calymperes(Calymperaceae).Most or all of the spores may escape before
the calyptra and operculum finally fall away.In such specimens there are empty capsules
still enclosed by the calyptra, with the calyptra still gripping the operculum.

Leucodonbrachypus is easy to distinguish from L. julaceus
by its longer, plicate leaves and usually immersed or emergent capsules.It is less common and less widespread than L. julaceus
and has a more northern range.The commonly
present gametangia and sporophytes,
lack of fragile axillarybranchlets,
and relatively short terminal cell on the leaf tips, distinguish it from the
similar L. andrewsianus.In L.
brachypusgametangia
or sporophytes, or both, are very commonly
present.The ranges of L. brachypus
and L. andrewsianusoverlap and the two species rarely grow intermixed.Leucodonbrachypusoccurs at sea level in the northren part of its range but only in the mountains to
the south, above ca. 300--400 m.

Plants of L. andrewsianus differ from those of
the similar and slightly more robust L.
brachypus most evidently in the common presence
of tufts of tiny branchlets congested in axils of distal
leaves and at the branch tips; in some specimens the branch tips and entire
older plants dissolve into branchlets.The branchlets
are mostly very short but sometimes are much elongated.In the absence of the branchlets
the slenderly elongate terminal cells of young
leaves are helpful for identification.Sporophytes of this moss are unknownandgametangia are extremely rare.Reproduction and dispersion are doubtless
accomplished by the caducousbranchlets.This taxon has
been treated in the flora area as Leucodonsciuroides (Hedwig) Schwägrichen,
a moss that occurs in Europe, Africa, and Asia, but apparently not in North America.